The present invention relates to a system used to deploy a radially expandable frame and an associated filter system which mounts onto the expandable frame. The present invention also relates to a locking system utilized in connection with the deployment system to lock the radially expandable frame during its use. The filter system is used to capture embolic material during catheterization of a patient.
During catheterization of a patient, a guide wire is directed through the patient""s blood vessel to the site of interest. For example, the physician may wish to utilize a balloon catheter in order to enlarge a partially obstructed blood vessel at a certain location in the patient""s vascular system. To do this, the physician utilizes a guide wire which is directed through the patient""s vascular system to the particular site for balloon catheterization. Various medical devices are percutaneously inserted into the patient""s blood vessel utilizing the guide wire. The balloon catheter, for example, is mounted at the distal end of an elongated tube. The guide wire is placed in the lumen of the balloon catheter tube such that the balloon catheter can be threaded over the guide wire, through the vascular system and placed at the site of interest by following the guide wire.
In order to enlarge a partially obstructed blood vessel, a physician may use various surgical techniques and biomedical devices or tools including balloon catheters, scrapers or other known medical devices. However, the utilization of these devices sometimes results in a release of an embolus (embolic material) which is an abnormal particle circulating in the blood. In order to reduce complications arising from these medical procedures, physicians sometime utilize filters disposed downstream of the site of interest. As used herein the term xe2x80x9cdownstreamxe2x80x9d refers to an item that is spaced a distance apart from a referenced item and in the direction of blood flow through the blood vessel.
U.S. Pat. No. 4,619,246 to Molgaard-Nielsen et al. discloses a collapsible filter basket. The basket includes a woven mesh but does not operate on a guide wire.
U.S. Pat. No. 4,723,549 to Wholey et al. discloses a filter which is expanded based upon inflation of a balloon acting as a donut mounted to expanding frame members of the filter disposed about the guide wire.
U.S. Pat. No. 5,053,008 to Bajaj discloses a filter which is expanded based upon inflation of a tubular balloon.
U.S. Pat. No. 5,108,419 to Reger et al. discloses a filter for capturing particles of plaque which includes a laterally (radially) collapsible bag with a plurality of longitudinally displaced filter cones therein. The bag has a draw string about its mouth which opens and closes the bag both laterally (to deploy or pull-up the conical filters) and longitudinally (to wrap the conical filters and the bag into a small-diameter shape). Each conical filter includes flexible tension supports which carry filter screens or mesh and which open and close based upon the respective longitudinal position of a generally static hub at the end of a guide wire running through the filter basket system. In another embodiment, a single conical filter is utilized with a filter stocking or collapsible bag thereabout. All the tension supports are flexible enough to wrap and twirl within the collapsible bag and wrap the conical filter(s) about the guide wire. Also, a draw string closes the collapsible bag in all embodiments. The flexible tension supports or radial ribs are resilient enough to provide force to spread the conical filter mesh across the lumen of the blood vessel.
U.S. Pat. No. 5,549,626 to Miller et al. discloses a filter deployed from the inside of a hollow tube by axial movement of an inner catheter.
U.S. Pat. No. 5,695,519 to Summers et al. discloses a wire, which controllably moves forward and aft, to open and close a generally conical filter by acting on the filter""s mouth.
U.S. Pat. No. 5,810,874 to Lefebvre discloses a filter including strips that are radially opened by moving an inboard ring towards an outboard ring. The rings retain forward and aft ends of the strips. The filter can be detached from the guide wire.
U.S. Pat. No. 5,814,064 to Daniel et al. discloses one filter system which utilizes various types of inflatable ribs, tubes or struts and a second filter system wherein the filter material is deployed by longitudinal movement of a push-pull wire relative to a generally static distal end of a tube (see Daniel FIGS. 15-16B). In one embodiment, struts carry filter mesh and are forced radially outward by axial movement of a wire attached to the apex of the conical filter relative to a static tube end. In a collapsed position, the filter is disposed outboard of the static tube. In another embodiment, wire filter mesh has a conical memory shape such that when deployed outboard of a closed end cylinder, a conical filter is created by the memory shaped metallic filter. In another embodiment, only the open end of the conical filter has a memory shape. A further embodiment utilizes memory shaped filter mesh, a cinch wire and a push guide wire.
U.S. Pat. No. 5,911,734 to Tsugita et al. discloses a conical mesh filter with a proximal end strut structure connected to the distal end of a guide wire. Accordingly, the distal end of a guide wire is not downstream of the filter (see Tsugita FIGS. 2-8B). In another embodiment, the filter (conical or concave) is attached to radially outwardly biased struts. In a closed state, the biased struts are retained within a sheath. Upon axial movement of the guide wire relative to the sheath, the struts are moved beyond the sheath, they spring open to expand and deploy the filter. (See Tsugita FIGS. 10-11B). In a further embodiment, an egg beater filter is deployed. One embodiment of the egg beater filter utilizes a compressive spring which pulls fore and aft ends of expandable struts together, thereby radially expanding a filter basket with one side carrying filter mesh thereon. In other words, the filter is spring actuated. (Tsugita FIG. 15A). In another egg beater embodiment, pressure wires xe2x80x9cspringxe2x80x9d radially outward deploying conical cage wires which retain a mesh filter. (Tsugita FIG. 16). A scroll filter is also disclosed. A further embodiment discloses a filter with an expansion frame apparently made of memory shaped material. Tsugita FIG. 19 discloses a filter with a distally extending inner sheath having filter strut ends attached thereto and an outer sheath having the other filter strut ends attached thereto. To open the filter, the outer sheath is moved distally towards the inner sheath thereby causing the filter struts to buckle radially outward. The struts may be packed densely to form a filter or filter mesh material may be draped over the struts. In a different embodiment, an outer sleeve is longitudinally slitted. (Tsugita FIG. 23, 23A). When the distal end of the slit outer sleeve is pulled proximally, the slitted region buckles radially outward to provide an egg beater filter. The expanded cage can be draped with filter mesh.
PCT Published Patent Application WO 96/01591 discloses a concave filter deployed by axially shortening the distance between the filter mouth and the filter apex (attached to a distal end of a guide wire). The filter mouth is sprung open by tethers fixed at one end to a static tube. A rod extends through the filter to its apex. The filter opens based upon the relative position of the filter apex on the rod (which extends beyond the apex to form the distal end of the guide wire) and the static tube.
It is an object of the present invention to provide a controllable deployment system for a radially expandable frame utilized during catheterization.
It is a further object of the present invention to provide an expandable frame with frame struts having, in a preferred embodiment, a centrally located bent region.
It is an additional object of the present invention to provide a manually controlled and deployed expandable frame which can be used in conjunction with a filter for capturing embolic material flowing through a blood vessel.
It is a an additional object of the present invention to provide a controllable deployment system for a radially expandable frame utilized during catheterization that includes a friction locking mechanism at the proximal end of an actuator sleeve such that the deployment system can be locked during radial deployment and radial closure of the radially expandable frame.
The controllable deployment system for a radially expandable frame utilized during catheterization includes a guide wire with a stop at its distal end, a radially expandable frame with distal and proximal frame ends through which the guide wire freely passes, an elongated actuation sleeve through which freely passes the guide wire, and a friction locking mechanism located at the proximal end of the system which is defined by the proximal ends of the actuation sleeve and guide wire. The expandable frame includes frame struts and has a closed, radially compact form and an open, radially expanded form. The frame, in the radially expanded form, has frame struts forming a pair of facing frustoconical frame structures. The guide wire extends through the expandable frame and the expandable frame is freely movable over the guide wire (likewise, the guide wire is freely movable within the frame), both rotatably and longitudinally, except distally beyond the stop near the distal end of the guide wire. This mobility of the guide wire with respect to the expandable frame enables to guide wire to be guided by the operator through the target vessel. The proximal end of the frame is coupled to an actuator sleeve. The actuator sleeve, at its proximal end, includes a friction locking mechanism having locking members with respective locking surfaces. The locking members are disposed on the proximal ends of the actuator sleeve and guide wire and include radially inboard and radially outboard locking surfaces, respectively. The locking mechanism permits the user to lock or hold static the actuator sleeve (and therefore, the expandable frame) with respect to the guide wire. The proximal ends of the guide wire and actuation sleeve may include detachable couplers allowing for removal of all or part of the locking mechanism from the deployment system. The system may also include tactile markers or indicia to indicate the frame""s relative position to a fixed point on the guide wire.